Hi, I am trying to enable the composite out of the cubieboard2 under LibreELEC. Has anybody experience with that topic already? It still confuses me a bit.
First, I read that u-boot supports composite out, which is disabled in the default u-boot kernel config. But by enabling those one would just be able to get composite out for the u-boot console, right? Or is the u-boot video-mode configuration somehow connected to the video output of the main kernel?
Next, probably critical configuration is the dts file. In the 5.7 mainline kernel they are here. Interesting part is in the include here which lists framebuffer-lcd-tve0. Is this dts configuration already setup to enable composite out?
Then, there is the video command line argument to setup the video output of the main kernel. But, where do those output strings (HDMI-1,VGA-1 ...) come from? Is it possible to retrieve a list of available outputs for the current video driver somehow?
So far I tried for luck to set the kernel argument video=Composite-1:720x480 as was the config on the H3 (see below), but that didn't work. Sadly in that case dmesg didn't complain about the video argument not being applied.
The status matrix for linux-sunxi lists a question mark for CVBS on A20, but it also states a no for the H3, though there seems to be working attempts to enable CVBS out on the H3 which raises my hopes for the A20.
There, some changes to the dts were needed, but frankly I have no experience with dts configs, as such I would be very happy for any hints to get CVBS out working on the cubieboard2? 
best
Martin